Biff support for XTDB v2 is in pre-release

I've been working on/preparing for migrating Biff to XTDB v2 since that became generally available in June. After investigating the deployment options and performance characteristics, I've added some XTDB v2 helper functions to the Biff library (under a new com.biffweb.experimental namespace) and I've made a version of the starter project that uses XTDB v2.

You can create a new XTDB v2 Biff project by running clj -M -e '(load-string (slurp "https://biffweb.com/new.clj"))' -M xtdb2. See this gist for a diff between the old/main starter project and this new one.

To give you a quick overview of what Biff provides:

• There are use-xtdb2 and use-xtdb2-listener components, roughly the same as we have already for XTDB v1.
• The ctx map will have a :biff/conn key in it (a Hikari connection pool object) which you can pass to xtdb.api/q to do queries.
• There is no longer a custom Biff transaction format. There is still a lightweight wrapper function, com.biffweb.experimental/submit-tx, which will apply Malli validation to any :put-docs / :patch-docs operations.

There's still plenty of work to do before XTDB v2 support in Biff is officially released and becomes the default:

• Next up, I'm migrating Yakread to XTDB v2. This will help me find any more issues that need to be addressed/make sure that Biff is indeed ready for XTDB v2.
• After that I need to update a bunch of documentation, including the tutorial project.

Since those next two steps will take a while, I wanted to do this "pre-release" for anyone who would like to get a head start on trying out Biff with XTDB v2. If you do so, let me know whatever questions/comments you have. Just note that the new functions in Biff's API are still experimental and might have breaking changes before I do the official release.

And for anyone who would rather not deal with migrating an existing app, Biff will still support XTDB v1. It's totally fine to stay on that.

Finally: I'll be at Clojure/Conj next week, at least if my flight doesn't get canceled. Come say hi.